5. Summary of Data Reported and Evaluation

5.1 Exposure data

HC Blue No. 1 was used as a semipermanent hair dye until the mid-1980s,
when its production and use were discontinued.

5.2 Human carcinogenicity data

No data were available to the Working Group.

5.3 Animal carcinogenicity data

HC Blue No. 1 was tested for carcinogenicity by administration
in the diet in two studies in mice, one of which was restricted
to females, and in one study in male and female rats. In one study
in male and female mice and in several experiments in the study
of females, it significantly increased the incidence of hepatocellular
adenomas and/or carcinomas in mice of each sex and increased the
incidence of thyroid follicular-cell adenomas in males. An increase
in the combined incidence of pulmonary adenomas and carcinomas
was seen in female but not in male rats.

Purified samples of HC Blue No. 1 did not bind to DNA or induce
mutation in bacteria. They did not induce mitotic recombination
in yeasts and did not induce mutation in insects. They induced
DNA damage, sister chromatid exchange and, weakly, gene mutation
but not chromosomal aberrations in cultured mammalian cells. DNA
damage was not induced in cultured human cells (HeLa). Micronuclei
were induced in the bone marrow of female mice of one strain exposed
in vivo.

5.5 Evaluation

There is inadequate evidence in humans for the carcinogenicity
of HC Blue No. 1.

There is sufficient evidence in experimental animals for
the carcinogenicity of HC Blue No. 1.